Stator for electric rotary machine

ABSTRACT

A stator for an electric rotary machine includes: stator core having a plurality of slots; and segmented coils of a plurality of phases (for example, coils  50  in the embodiment), wherein: the segmented coils of a plurality of phases have pluralities of coil bars which are inserted individually in the plurality of slots in the stator core and which extend substantially in a straight line and pluralities of connection coils which connect together the coil bars of the same phase to thereby make up extending portions; the connection coils each comprise an inner connection coil and an outer connection coil which are disposed in different axial positions; and the inner connection coil faces an outer connection coil of a different phase in an axial direction and the outer connection coil faces the inner connection coil of a different phase in the axial direction.

BACKGROUND

1. Field of the Invention

The present invention relates to a stator for an electric rotary machinewhich is installed in an electric vehicle or a hybrid vehicle.

2. Description of the Related Art

Conventionally, as a stator for an electric rotary machine which isfabricated using segment coils, there have been known stators forelectric rotary machines in which coils are formed by inserting pluralsegments which are made up of electric conductors which are formed intoa U-shape in slots in a stator core, thereafter bending leg portions andjoining together end portions of the segments (refer to JP-A-2003-158840and U.S. Pat. No. 6,894,417).

In stators for electric rotary machines described in JP-A-2003-158840and U.S. Pat. No. 6,894,417, coils are formed through a formingoperation of forming electric conductors into a U-shape, a bendingoperation of bending leg portions and a joining (welding) operation ofjoining together end portions of the electric conductors. Because ofthis, the end portions of the electric conductors are joined together insuch a state that the end portions project in the axial direction, andtherefore, the size of the stator is increased in the axial directiondue to extending portions, and the length of the extending portions isincreased. Thus, there still exists room for improvement.

SUMMARY

The invention has been made in view of the problems described above, andan object thereof is to provide a stator for an electric rotary machinewhich can be reduced in size by suppressing the projection of extendingportions in the axial direction and which can enhance the performancethereof by suppressing the copper loss as a result of the length of theextending portions being reduced.

With a view to attaining the object, according to a first aspect of theinvention, there is provided a stator (for example, a stator 10 in anembodiment which will be described later) for an electric rotary machineincluding:

a stator core (for example, a stator core 21 in the embodiment) havingplural slots (for example, slots 23 in the embodiment); and

segmented coils of plural phases (for example, coils 50 in theembodiment), wherein

the segmented coils of plural phases have plural coil bars (for example,coil bars 25 in the embodiment) which are inserted individually in theplural slots in the stator core and which extend substantially in astraight line and plural connection coils (for example, connection coils40 in the embodiment) which connect together the coil bars of the samephase to thereby make up extending portions, wherein

the connection coils each include an inner connection coil (for example,an inner connection coil 42 in the embodiment) and an outer connectioncoil (for example, an outer connection coil 41 in the embodiment) whichare disposed in different axial positions, and wherein

the inner connection coil faces an outer connection coil of a differentphase in an axial direction and the outer connection coil faces theinner connection coil of a different phase in the axial direction.

According to a second aspect of the invention, there is provided astator core for an electric rotary machine as set forth in the firstaspect, wherein

a pair of base plates (for example, base plates 31L, 31R in theembodiment) are provided at both ends of the stator core, wherein

in each of the pair of base plates, plural grooves (for example, outersurface grooves 37 and inner surface grooves 38 in the embodiment) areformed on each of an outer surface (for example, an outer surface 35 inthe embodiment) and an inner surface (for example, an inner surface 36in the embodiment) thereof which face each other, wherein

the outer connection coils are disposed in the grooves (for example, theouter surface grooves 37 in the embodiment) which are formed on theouter surface, and wherein

the inner connection coils are disposed in the grooves (for example, theinner surface grooves 38 in the embodiment) which are formed on theinner surface.

According to a third aspect of the invention, there is provided a statorfor an electric rotary machine as set forth in the first or secondaspect, wherein

the coil bars which are inserted individually in the slots each includea radially outer coil bar (for example, a radially outer coil bar 26 inthe embodiment) and a radially inner coil bar (for example, a radiallyinner coil bar 27 in the embodiment) which are aligned in a radialdirection, wherein

one of the radially outer coil bar and the radially inner coil bar isconnected to the outer connection coil at one end and is connected tothe inner connection coil at the other end thereof, and wherein

the other of the radially outer coil bar and the radially inner coil baris connected to the inner connection coil at one end and is connected tothe outer connection coil at the other end thereof.

According to a fourth aspect of the invention, there is provided astator for an electric rotary machine as set forth in the third aspect,wherein

the outer connection coil connected to the radially outer coil bar atthe one end thereof extends radially outwards and in one of a clockwisedirection and a counterclockwise direction to thereby be connected to aninner connection coil of the same phase, wherein

the inner connection coil connected to the radially outer coil bar atthe other end thereof extends radially outwards and in the other of theclockwise direction and the counterclockwise direction to thereby beconnected to an outer connection coil of the same phase, wherein

the inner connection coil connected to the radially inner coil bar atthe one end thereof extends radially outwards and in the other of theclockwise direction and the counterclockwise direction to thereby beconnected to an outer connection coil of the same phase, and wherein

the outer connection coil connected to the radially inner coil bar atthe other end thereof extends radially outwards and in the one of theclockwise direction and the counterclockwise direction to thereby beconnected to an inner connection coil of the same phase.

According to a fifth aspect of the invention, there is provided a statorfor an electric rotary machine as set forth in the fourth aspect,wherein

in each of the base plates, a radially inner through hole (for example,a radially inner through hole 33 in the embodiment) and a radially outerthrough hole (for example, a radially outer through hole 32 in theembodiment) in which the radially inner coil bar and the radially outercoil bar which are disposed in the same slot in the stator core areinserted, respectively, are formed so as to be aligned in the radialdirection, wherein

the inner connection coil and the outer connection coil which areconnected to the radially outer coil bar are formed so as to extendalong an involute curve, and wherein

the inner connection coil and the outer connection coil which areconnected to the radially inner coil bar are formed so as to extendalong an involute curve while being bent at a radially inner end of theinvolute curve so as to extend radially outwards from the radially innerthrough hole while extending around the radially outer through hole.

According to a sixth aspect of the invention, there is provided a statorfor an electric rotary machine as set forth in any of the third to fifthaspects, wherein

the radially outer coil bar and the radially inner coil bar have thesame length.

According to a seventh aspect of the invention, there is provided astator for an electric rotary machine as set forth in any of the firstto sixth aspects, wherein

the plural connection coils are disposed within a region where thestator core is projected in the axial direction.

According to the first aspect of the invention, the extending portionswhich connect together the coil bars of the same phase are made up ofthe inner connection coils and the outer connection coils which aredisposed in the different axial positions, whereby the axial projectionof the extending portions can be suppressed, thereby making it possibleto reduce the size of the stator. In addition, the copper loss isreduced as a result of the reduction in length of the extendingportions, whereby the efficiency of the electric rotary machine isenhanced.

According to the second aspect of the invention, the inner connectioncoils and the outer connection coils are disposed in the different axialpositions efficiently in such a state that they are isolated from eachother by the base plate, whereby not only can the size of the stator bereduced, but also the assembling properties of the segmented coils canbe enhanced.

According to the third aspect of the invention, the outer and innerconnection coils can be connected to the two coil bars which extend fromthe slot in the form of a wave winding.

According to the fourth aspect of the invention, the outer and innerconnection coils can be connected to the coil bars which extend from theslots radially outwards, whereby the rotor can easily be disposed insidethe stator, thereby making it possible to connect the connection coilswith the coil bars in the form of a wave winding.

According to the fifth aspect of the invention, the inner connectioncoils and the outer connection coils do not interfere with each otherwithin the base plate, thereby making it possible to reduce the areaoccupied by them.

According to the sixth aspect of the invention, the radially outer coilbar and the radially inner coil bar are made to have the same length, sothat coil bar parts can be commonized.

According to the seventh aspect of the invention, the radial size of thestator can be reduced, and the rotor can easily be disposed inside thestator.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingwhich is given by way of illustration only, and thus is not limitativeof the present invention and wherein:

FIG. 1 is a perspective view of a stator for an electric rotary machineaccording to the invention;

FIG. 2 is an exploded perspective view of the stator shown in FIG. 1;

FIG. 3A is an exploded perspective view of one of base plate assembliesshown in FIG. 2, and FIG. 3B is an exploded perspective view of theother base plate assembly;

FIG. 4 is a perspective view of a coil bar;

FIG. 5 is a vertical sectional view of the stator shown in FIG. 1 whichis taken along the line A-A in FIG. 6;

FIG. 6 is a front view of the one base plate assembly shown in FIG. 3A;

FIG. 7 is a rear view of the one base plate assembly shown in FIG. 3A;

FIG. 8 is a perspective view of double-slot type, segmented coils ofplural phases;

FIG. 9 is a perspective view of coils of one phase which are taken outfrom the coils of the plural phases shown in FIG. 8;

FIG. 10 is an exemplary diagram showing the configuration of the coilsof the plural phases;

FIG. 11A is a partial enlarged view of FIG. 6, and FIG. 11B is asectional view taken along the line B-B in FIG. 11A;

FIG. 12A is an exemplary diagram showing a state in which a coil bar andconnection coils are connected together through crimping, FIG. 12B is anexemplary diagram showing a state in which a coil bar havingsemi-spherical end portions is connected to connection coils throughpress fitting, and FIG. 12C is an exemplary diagram showing a state inwhich a coil bar having semi-circular end portions and a rectangularcross section is connected to connection coils by being press fitted inholes in the connection coils;

FIG. 13 is a perspective view of the stator in which cooling plates aredisposed on end faces of the base plate assemblies;

FIG. 14 is a vertical sectional view of a main part of the statorincluding the cooling plates shown in FIG. 13;

FIG. 15 is a perspective view of coils of one phase making upsingle-slot type coils of plural phases; and

FIG. 16 is a perspective view of coils of one phase making uptriple-slot type coils of plural phases.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the invention will be described byreference to the accompanying drawings. The drawings are to be seen inan orientation in which reference numerals given look properly.

As shown in FIGS. 1, 2 and 5, a stator 10 for an electric rotary machineaccording to this embodiment includes a stator core assembly 20 and apair of base plate assemblies 30L, 30R, and the base plate assemblies30L, 30R are disposed and assembled individually to ends of the statorcore assembly 20. An insulation sheet 65 which is made of, for example,silicone is disposed between the stator core assembly 20 and each of thebase plate assemblies 30L, 30R to insulate the stator core assembly 20and the base plate assemblies.

The stator core assembly 20 includes a stator core 21 and plural (48 inthe embodiment shown in the figures) coil bars 25.

The stator core 21 is made up, for example, of plural silicon steelsheets which are blanked out by a blanking press and, are laminatedtogether and includes 48 teeth 22 which are provided on a radially innerside thereof and 48 slots 23 which are formed between the teeth 22, 22which lie adjacent to each other. The slots 23 are formed so as topenetrate the stator core 21 in an axial direction thereof and have asubstantially elliptic shape which is elongated in a radial direction ofthe stator core 21 when viewed from the axial direction thereof. Theslots 23 also have opening portions 24 which are opened to an innercircumferential surface of the stator core 21.

Also, referring to FIG. 4, the coil bar 25 includes a radially outercoil bar 26 and a radially inner coil bar 27 which have the same shapeand length. The radially outer coil bar 26 and the radially inner coilbar 27 are disposed parallel while being offset from each other in theaxial direction by such an extent as a thickness of a connection coil40, which will be described later. The radially outer coil bar 26 andthe radially inner coil bar 27 are formed integrally by being covered onthe periphery thereof by an insulation material 28 which is injectionmolded from a resin, with both ends of each coil bar left uncovered.Specifically, the length of each of the radially outer coil bar 26 andthe radially inner coil, bar 27 is set to a length which issubstantially equal to a sum of an axial length of the stator core 21and a thickness of three connection coils 40, and small-diameterportions 26 a, 27 a are formed at both the ends of the radially outercoil bar 26 and the radially inner coil bar 27, respectively, the lengthof the small-diameter portions 26 a, 27 b being substantially equal tothe thickness of the connection coil 40.

The plural (48 in the embodiment shown in the figures) coil bars 25,each made up of the radially outer coil bar 26 and the radially innercoil bar 27, are, as shown in FIG. 5, inserted individually in the 48slots 23 in the stator core 21 so that the radially outer coil bars 26are situated radially outwards and are then aligned in a circumferentialdirection of the stator core 21. Thus, the plural coil bars 25 make upthe stator core assembly 20.

The radially outer coil bars 26 are inserted individually in the slots23 so that the small-diameter portion 26 a projects approximately bysuch an extent as a thickness of two connection coils 40 from one endface 21 a (a left end face in FIG. 5) of the stator core 21, while thesmall-diameter portion 26 a projects approximately by such an extent asthe thickness of the connection coil 40 from the other end face 21 b (aright end face in FIG. 5)

Additionally, the radially inner coil bars 27 are inserted individuallyin the slots 23 so that the small-diameter portion 27 a projectsapproximately by such an extent as the thickness of the connection coil40 from the one end face 21 a of the stator core 21, while thesmall-diameter portion 26 a projects approximately by such an extent asthe thickness of two connection coils 40 from the other end face 21 b.The insulation material 28 is interposed between the radially outer coilbar 26 and the radially inner coil bar 27 and the slot 23 in the statorcore 21 so as to ensure the insulation between the radially outer andinner coil bars 26, 27 and the stator core 21. Consequently, theradially outer coil bar 26 and the radially inner coil bar 27 arecovered by the insulation member 28 in such a state that the radiallyouter and inner coil bars 26, 27 are offset from each other in the axialdirection so that the axial positions of the end portions thereof differfrom each other.

The insulation material 28 which covers the radially outer coil bar 26and the radially inner coil bar 27 has substantially the same shape asthat of the slot 23 and is sized slightly larger than the slot 23. Thus,the insulation material 28 can easily be inserted in the slot 23 throughpress fitting. In addition, the radially outer coil bar 26 and theradially inner coil bar 27 are thicker than a conventional coil which ismade up of a winding which is wound therearound, and hence, there isprovided an advantage that the space factor relative to the slot 23 isincreased.

As shown in FIGS. 1 to 7, the base plate assemblies 30L, 30R which aredisposed individually at the ends of the stator core assembly 20 includebase plates 31L, 31R and plural connection coils 40. The base plateassembly 30R differs from the base plate assembly 30L in that the formerdoes not include a connecting terminal portion, which will be describedlater, and in that the shapes of grooves formed and the connection coilsprovided on the former differ from those of the latter. The otherconfigurations of both the base plate assemblies are the same, andtherefore, the base plate assembly 30L will mainly be describedhereinafter.

As shown in FIGS. 6 and 7, the base plate 31L is formed from a resinhaving insulating properties and is a substantially annular memberhaving substantially the same inside and outside diameters as those ofthe stator core 21. A deployment portion 31 a is provided at an upperportion of the base plate 31L as seen in the figures so as to extendradially outwards therefrom into the shape of a segment. A connectingterminal portion is formed on the deployment portion 31 a for connectionto external equipment or the like.

48 pairs of radially outer through holes 32 and radially inner throughholes 33 are formed to penetrate the base plate 31L at a radially innerside of the base plate 31L so a correspond, respectively, to theradially outer coil bars 26 and the radially inner coil bars 27 of thecoil bars 25 which are inserted in the slots 23 in the stator core 21.

The radially outer through hole 32 and the radially inner through hole33 which make a pair are situated on the same straight line L whichextends from a center O of the base plate 31 in a radial direction.Further, a radially outermost hole 34 is formed on an outside diameterside of the base plate 31L. Thus, the radially outer and inner throughholes 32, 33 and radially outermost hole 34 establish a communicationbetween an outer surface 35 and an inner surface 36 of the base plate31L (refer to FIG. 5). Additionally, in a circumferential position wherethe deployment portion 31 a is formed, 12 connecting terminal joiningholes 39 are formed which are situated further radially outwards thanthe position of the radially outermost hole 34 in the deployment portion31 a.

As shown in FIGS. 5 to 7, plural (48) outer surface grooves 37 and innersurface grooves 38 are formed along involute curves so as to lie closeto one another on the outer surface 35 and the inner surface 36 of thebase plate 31L, respectively. The outer surface grooves 37 and the innersurface grooves 38 are formed to have a U-shaped section which is openedto the outer surface 35 and the inner surface 36, respectively. Theadjacent outer surface grooves 37 and the adjacent inner surface grooves38 are isolated by walls 31 b which is erected from the base plate 31L,and the outer surface groves 37 and the inner surface grooves 38 whichface each other in an axial direction are isolated by a bulkhead 31 c,whereby the outer surface grooves 37 and the inner surface grooves 38are electrically insulated one by one

In addition, the base plate 31 is given an axial width which issubstantially equal to a sum of groove depths of the outer surfacegroove 37 and the inner surface groove 38 which correspond,respectively, to an outer connection coil 41 and an inner connectioncoil 42, which will both be described later, and a thickness of thebulkhead 31 c.

In the base plate assembly 30L, as shown in a front view of the baseplate in FIG. 6, each outer surface groove 37 on the base plate 31L isformed in a curved fashion along the involute curve so as to connect oneradially outer through hole 32 with one radially outermost hole 34 whichis formed on a straight line L which passes through a radially outerthrough hole 32 which lies three radially outer through holes ahead in aclockwise direction from the one radially outer through hole 32. In theplural outer surface grooves 37, however, 12 outer surface grooves 37 awhich extend towards the deployment portion 31 a extend in an involutefashion from the corresponding radially outer through holes 32 tostraight lines L which pass through the radially outer through holes 32which lie three radially outer through holes ahead in the clockwisedirection from the radially outer through holes 32 from which the outersurface grooves 37 a start to extend and thereafter are bent radiallyoutwards so as to connect to the corresponding connecting terminaljoining holes

As shown in a rear view of the base plate in FIG. 7, each inner surfacegroove 38 on the base plate 31 is formed in such a curved fashion as toavoid the interference with the corresponding radially outer throughhole 32 so as to connect one radially inner through hole 33 with oneradially outermost hole 34 which is formed on a straight line L whichpasses through a radially inner through hole 33 which lies threeradially inner through holes ahead in a clockwise direction (in acounterclockwise direction when seen from the front side of the baseplate 31L shown in FIG. 6) from the one radially inner through hole 33.In the plural inner surface grooves 38, however, 12 inner surfacegrooves 38 a which extend towards the deployment portion 31 a extendsimilarly in a curved fashion from the corresponding radially innerthrough holes 33 to straight lines L which pass through the radiallyinner through holes 33 which lie three radially inner through holesahead in the clockwise direction (in the counterclockwise direction whenseen from the front side of the base plate 31L shown in FIG. 6) from theradially inner through holes 33 from which the inner surface grooves 38a start to extend and thereafter are bent radially outwards so as toconnect to the corresponding connecting terminal joining holes 39,

Namely, as shown in FIG. 6, the radially outer through hole 32 and theradially inner through hole 33 which are spaced six radially outer orinner through holes apart from each other in the clockwise direction (orin the counterclockwise direction) are connected to each other via theradially outermost hole 34 to which the outer surface groove 37 and theinner surface groove 38 commonly connect. In addition, the pair of outersurface groove 37 a and inner surface groove 38 a which connect to thecommon connecting terminal joining hole 39 connect the radially outerthrough hole 32 with the radially inner through hole 33 which are spacedsix radially outer or inner through holes apart from each other in theclockwise direction (or in the counterclockwise direction)

In the base plate assembly 30R, each outer surface groove 37 on the baseplate 31R has the same shape of each inner surface groove 38 on the baseplate 31L, and each inner surface groove 38 on the base plate 31R hasthe same shape as each outer surface groove 37 on the base plate 31L.

The connection coil 40 is formed of a conductive material such as copperinto the shape of a plate. The connection coils 40 are divided intoouter connection coils 41 (41 a, 41 b) which are inserted in the outersurface grooves 37, 37 a and inner connection coils 42 (42 a, 42 b)which are inserted in the inner surface grooves 38, 38 a. When referredto herein, the outer connection coils 41 are the connection coils 40which are disposed on an axially outer side of the stator 10 when thestator core assembly 20 and the base plate assemblies 30 are assembledtogether, and the inner connection coils 42 are the connection coils 40which are disposed on an axially inner side of the stator 10.

As shown in FIG. 6, the outer connection coils 41 a are formed along theinvolute curves having the same shape of the outer surface grooves 37,and connection holes 43 a, 43 b are formed at both end portions of theouter connection coils 41 a. The connection hole 43 a has a diameterwhich is substantially the same as that of the small-diameter portion 26a of the radially outer coil bar 26, and the connection hole 43 b has adiameter which is substantially the same as that of a connecting pin 45,which will be described later, for connecting together the outerconnection coil 41 a and the inner connection coil 42 a. In addition,the outer connection coils 41 b are formed in a curved fashion to havethe same shape as that of the outer surface grooves 37 a, and connectionholes 43 a and connecting terminal holes 43 c are formed at both endportions of the outer connection coils 41 b.

As shown in FIG. 7, the inner connection coils 42 a are formed along theinvolute curves having the same shape of the inner surface grooves 38,and connection holes 44 a, 44 b are formed at both end portions of theinner connection coils 42 a. The connection hole 44 a has a diameterwhich is substantially the same as that of the small-diameter portion 27a of the radially inner coil bar 27, and the connection hole 44 b has adiameter which is substantially the same as that of the connecting pin45. In addition, the inner connection coils 42 b are formed in a curvedfashion to have the same shape as that of the inner surface grooves 38a, and connection holes 44 a and connecting terminal holes 44 c areformed at both end portions of the inner connection coils 42 b.

Consequently, except for the portion of the base plate 31L where theconnecting terminal joining holes 39, the inner connection coils 42 aand the outer connection coils 41 a, 41 b that are all connected to theradially outer coil bars 26 are formed along the involute curves, andthe inner connection coils 42 a, 42 b and the outer connection coils 41a that are all connected to the radially inner coil bars 27 are formedalong the involute curves so as to extend radially outwards from theradially inner through holes 33 on a radially inner side of the involutecurves.

The outer connection coils 41 a, 41 b are inserted in the outer surfacegrooves 37, 37 a, respectively, and the inner connection coils 42 a, 42b are inserted in the inner surface grooves 38, 38 a, respectively. Theconductive connecting pins 45 which are made of copper or aluminum areinserted in the radially outermost holes 34 so as to electricallyconnect the outer connection coils 41 a and the inner connection coils42 a.

By so doing, the base plate assemblies 30L, 30R are built up in such astate that the connection holes 43 a of the outer connection coils 41 aand the connection holes 44 a of the inner connection coils 42 a whichare disposed six connection holes apart from each other in the clockwisedirection (or in the counterclockwise direction) are electricallyconnected via the outer connection coils 41 a, the connecting pins 45and the inner connection coils 42 a.

In place of providing the connecting pins 45 as in this embodiment, aconfiguration may be adopted in which projecting portions having thesame shape of the connecting pin 45 are formed integrally on either ofthe outer connection coils 41 a and the inner connection coils 42 a, sothat the projecting portions so formed are inserted in connection holes43 b, 44 b which are provided on the other of the outer connection coils41 a and the inner connection coils 42 a, whereby the outer connectioncoils 41 a and the inner connection coils 42 a are electricallyconnected to each other.

The pair of base plate assemblies 30L, 30R, which are configured as hasbeen described heretofore, are disposed in the predetermined positionson both the ends of the stator core assembly 20 so as to be assembledthereto. As shown in FIG. 5, in the base plate assembly 30L which isdisposed at the one end face 21 a (the left end face in the figure) ofthe stator core 21, the small-diameter portions 26 a of the radiallyouter coil bars 26 are inserted in the connection holes 43 a of theouter connection coils 41 a, 41 b, and the small-diameter portions 27 aof the radially inner coil bars 27 are inserted in the connection holes44 a of the inner connection coils 42 a, 42 b. Thereafter, thesmall-diameter portions 26 a, 27 a are crimped to be fixed in place inthe corresponding connection holes 43 a, 44 a. Namely, the outerconnection coils 41 a, 41 b and the inner connection coils 42 a, 42 bconnect together the coil bars 25 of the same phase (for example, aU-phase) to thereby form extending portions of a coil 50.

In the base plate assembly 30R which is disposed at the other end face21 b (the right end face in the figure) of the stator core 21, thesmall-diameter portions 26 a of the radially outer coil bars 26 areinserted in the connection holes 44 a of the inner connection coils 42a, and the small-diameter portions 27 a of the radially inner coil bars27 are inserted in the connection holes 43 a of the outer connectioncoils 41 a. Thereafter, the small-diameter portions 26 a, 27 a arecrimped to be fixed in place in the corresponding connection holes 43 a,44 a. Namely, the outer connection coils 41 a and the inner connectioncoils 42 a connect together the coil bars 25 of the same phase (forexample, the U-phase) to thereby form extending portions of the coil 50.

Consequently, with respect to the radially outer coil bar 26 and theradially inner coil bar 27 which are disposed in the same slot 23, theouter connection coil 41 a which is connected to the one end (the leftend in the figure) of the radially outer coil bar 26 extends radiallyoutwards and in the clockwise direction to connect to the innerconnection coil 42 a of the same phase, while the inner connection coil42 a which is connected to the other end (the right end in the figure)of the radially outer coil bar 26 extends radially outwards and in thecounterclockwise direction to connect to the outer connection coil 41 aof the same phase. In addition, the inner connection coil 42 a which isconnected to the one end (the left end in the figure) of the radiallyinner coil bar 27 extends radially outwards and in the counterclockwisedirection to connect to the outer connection coil 41 a of the samephase, while the outer connection coil 41 a which is connected to theother end (the right end in the figure) of the radially inner coil bar27 extends radially outwards and in the clockwise direction to connectto the inner connection coil 42 a of the same phase.

In this way, the stator 10 is made up by assembling the pair of baseplate assemblies 30L, 30R to both the ends of the stator core assembly20, whereby segmented coils 50 make up four coil loops for each phasewhich has the same construction (U-phase coils 50U, V-phase coils 50V,and W-phase coils 50W). In these coil loops of the three phases (theU-phase coils 50U, the V-phase coils 50V, and the W-phase coils 50W),two coil loops make up a set, and hence, two sets of U-phase coils 50U,two sets of V-phase coils 50V, and two sets of W-phase coils 50W arewave wound in the counterclockwise direction in this order (refer toFIGS. 8 and 10). Then, the radially outer coil bar 26 and the radiallyinner coil bar 27 which are covered together by the insulation material28 to be disposed within the same slot 23 each include two coils whichmake up one set. FIG. 8 is a perspective view of double-slot type,segmented coils of plural phases (U-, V- and W-phase) which are takenout from the stator for better understanding, and FIG. 9 is aperspective view of coils of one phase (for example, U-phase) which aretaken out, in turn, from the coils of the plural phases. FIG. 10 is anexemplary diagram showing the configuration of the coils of the pluralphases, FIG. 11A is a partial enlarged view of FIG. 6, and FIG. 11B is asectional view taken along the line B-B in FIG. 11A.

Additionally, in the stator 10 which is configured in the way describedheretofore, the outer connection coils 41 a, 41 b and the innerconnection coils 42 a, 42 b are disposed within a region where thestator core 21 is projected in the axial direction and are disposed indifferent positions with respect to the axial direction.

In the sectional view of the base plate assembly 30L taken along theline B-B which is shown in FIG. 11A, as shown in FIG. 11B, on the outersurface of the base plate 31L, two V-phase outer connection coils 41 band one W-phase outer connection coil 41 b are aligned in this orderfrom in a radially inward to outward direction at the small-diameterportion 26 a of the U-phase radially outer coil bar 26 from a radiallyinner side, while on the inner surface of the base plate 31L, oneU-phase connection coil 42 b and two W-phase inner connection coils 42 bare aligned in this order from the radially inner. Consequently, as isclear from FIG. 11A, the inner connection coils 42 a, 42 b face theouter connection coils 41 a, 41 b of the different phase in the axialdirection, and the outer connection coils 41 a, 41 b face the innerconnection coils 42 a, 42 b of the different phase in the axialdirection.

In addition, outer surfaces of the plural outer connection coils 41 a,41 b which are disposed at the axially outer ends of the stator 10 arelevel with the end faces of the base plates 31L, 31R.

Additionally, as is shown in FIG. 5, the coils 50 are assembled to thestator 10 so that the outer connection coils 41 a, 41 b which connect tothe radially outer coil bars 26 are situated axially outwards at the oneend face 21 a of the stator core 21, while at the other end face 21 b ofthe stator core 21, the outer connection coils 41 a which connect to theradially inner coil bars 27 are situated axially outwards.

FIGS. 12A to 12C show conceptual diagrams showing connectingconstructions between a coil bar and connection coils. Hereinafter, theradially outward coil bar 26 is taken as an example for description.However, connecting constructions which will be described below can alsobe applied to the radially inner coil bar 27. In a radially outer coilbar 26 shown at FIG. 12A, tapered portions 26 b which are taperedtowards ends of the radially outer coil bar 26 are formed at both endportions, and a connection hole 43 a in an outer connection coil 41 a or41 b and a connection hole 44 a in an inner connection coil 42 a aremade into a tapered hole having a gradient which is substantially equalto that of the end portions of the radially outer coil bar 26. Theradially outer coil bar 26 and the connection coils 40 are assembledtogether so that the base plates 31L, 31R are assembled to the statorcore 21 and the connection coils 90 are then pressed axially relative tothe radially outer coil bar 26 by pressing members 61 of jigs by virtueof elastic forces of springs 64, whereby the connection holes 43 a, 44 aof the connection coils 40 are fitted on the tapered portions 26 b ofthe radially outer coil bar 26. Then, the end portions of the radiallyouter coil bar 26 are crimped by being crushed to be deformed at ends bya punch 62, whereby the coil bar 26 and the connection coils 40 arefixed together.

As this occurs, the fitting portions between the radially outer coil bar26 and the connection coils 40 are tapered, and therefore, even in casecenters of the radially outer coil bar 26 and the connection coils 40are offset slightly, the radially outer coil bar 26 and the connectioncoils 40 are centered by virtue of pressures applied thereto by thepressing members 61 so that the radially outer coil bar 26 and theconnection coils 40 are joined together at the tapered portions 26 b inan ensured fashion to thereby establish an electric communicationtherebetween. In addition, such joining can be executed at plurallocations (96 locations in this embodiment) through a single pressingoperation. Thus, the joining work can be executed efficiently, therebymaking it possible to increase the fabrication efficiency remarkably. Itshould be noted that the coil bar 25 and the connection coils 40 do notnecessarily have to be connected together by press fitting and crimping,and hence, they may be connected together by press fitting or crimping.Thus, a connection of the coil bar 25 and the connection coils 40 basedon press fitting will be described below.

End portions of a radially outer coil bar 26, shown in FIG. 12B, areformed into a semi-spherical shape, and connection holes 43 a, 44 a ofconnection coils 40 are formed into a semi-spherical depressed portion.In this construction, the semi-spherical end portions of the radiallyouter coil bar 26 are press fitted in the connection holes 43 a, 44 a ofthe connection coils 40, whereby the radially outer coil bar 26 and theconnection coils 40 are joined together. In this construction, too, theradially outer coil 26 and the connection coils 40 can be centered. Inaddition, such joining can be executed at plural locations through asingle pressing operation, whereby the radially outer coil 26 and theconnection coils 40 can be joined together extremely efficiently.

A radially outer coil bar 26, shown in FIG. 12C, is formed to have arectangular cross section, and end portions thereof are formed into asemicircular shape. In addition, connection holes 43 a, 44 a ofconnection coils 40 are similarly formed into a semicircular depressedportion, and the radially outer coil bar 26 and the connection coils 40are joined together by press fitting the end portions of the radiallyouter coil 26 into the connection holes 43 a, 44 a which are thesemicircular depressed portions. Being given the rectangular crosssection, the radially outer coil bar 26 of this embodiment has anangular shape which closely matches that of the slot 23, and therefore,the space factor of the slot 23 can also be enhanced.

FIG. 13 is a perspective view of the stator in which cooling plates aredisposed at end faces of the base plate assemblies, and FIG. 14 is avertical sectional view of a main part of the stator. As shown in FIGS.13 and 14, a pair of cooling plates 60 are disposed so as to be incontact with the base plate assemblies 30 which are provided at both theend faces of the stator 10. A refrigerant passageway 63 is formed in aninterior of the cooling plate 60 so that a refrigerant is allowed tocirculate therein. Then, a refrigerant which is sent under pressure froma refrigerant supply system, not shown, is circulated in, for example, adirection indicated by an arrow C (refer to FIG. 13) in the refrigerantpassageway 63 in the cooling plate 60. Thus, the stator 10 can be cooledpositively via the outer connection coils 41 a, 41 b (the extendingportions) of the stator 10 with which the pair of cooling plates 60 arein contact.

Additionally, front surfaces of the outer connection coils 41 a, 41 bare flat, and therefore, the outer connection coils 41 a, 41 b arebrought into surface contact with the cooling plates 60. Because ofthis, compared with a conventional coil around which a winding is wound,the contact area with the cooling plates 60, that is, the heatconduction area is large, thereby making it possible to cool the stator10 efficiently.

Additionally, in the coils 50, at the one end face 21 a of the statorcore 21, the outer connection coils 41 a, 41 b which connect to theradially outer coil bars 26 are situated axially outwards, while at theother end face 21 b of the stator core 21, the outer connection coils 41a which connect to the radially inner coil bars 27 are situated axiallyoutwards. Therefore, the radially outer coil bars 26 and the radiallyinner coil bars 27 are cooled uniformly via the outer connection coils41 a, 41 b to thereby suppress the heat distribution of the coils.Further, the coils 50 are free from concerns caused when an oil coolingprocess using an ATF oil or the like is selected that the coils and theinsulation materials are badly affected by the ATF oil which is sprayedto the coils, the reliability and durability of the stator being therebyenhanced.

Thus, as has been described heretofore, the stator 10 according to thisembodiment includes the stator core 21 and the segmented coils 50 ofplural phases, and the segmented coils 50 of plural phases have theplural coil bars 25 which are inserted individually in the plural slots23 in the stator core 21 and which extend substantially in the straightline and the plural connection coils 40 which connect together the coilbars 25 of the same phase to thereby make up the extending portions. Theconnection coils 40 each includes the inner connection coil 42 and theouter connection coil 41 which are disposed in the different axialpositions, and the inner connection coil 42 faces the outer connectioncoil 91 of the different phase in the axial direction, while the outerconnection coil 41 faces the inner connection coil 42 of the differentphase in the axial direction. Therefore, the extending portions whichconnect together the coil bars 25 of the same phase are disposed in thedifferent axial positions, whereby the axial projection of the extendingportions can be suppressed, thereby making it possible to reduce thesize of the stator 10. In addition, the copper loss can be suppressed asa result of the length of the extending portions being reduced, theperformance of the electric rotary machine being thereby enhanced.

In addition, the pair of base plates 31L, 31R are provided at both theends of the stator core 21, and in each of the pair of base plates 31L,31R, the plural grooves 37, 38 are formed on the outer surface 35 andthe inner surface 36 thereof which face each other, respectively. Theouter connection coils 41 are disposed in the grooves 37 which areformed on the outer surface 35, while the inner connection coils 42 aredisposed in the grooves 38 which are formed on the inner surface 36.Therefore, the extending portions are disposed in the different axialpositions efficiently in such estate that the extending portions areinsulated by each of the base plates 31L, 31R, whereby not only can thesize of the stator 10 be reduced, but also the assembling properties ofthe segmented coils 50 can be enhanced.

Further, the coil bars 25 which are inserted individually in the slots23 each include the radially outer coil bar 26 and the radially innercoil bar 27 which are aligned in the radial direction, and the radiallyouter coil bar 26 is connected to the outer connection coil 41 at oneend and is connected to the inner connection coil 42 at the other endthereof, while the radially inner coil bar 27 is connected to the innerconnection coil 42 at one end and is connected to the outer connectioncoil 41 at the other end thereof. Therefore, the outer and innerconnection coils 41, 42 can be connected to the two coil bars 26, 27which extend from the slot 23 in the form of a wave winding.

In addition, the radially outer coil bar 26 and the radially inner coilbar 27 are connected to the outer connection coils 41 which arepositioned axially outwards of the stator 10 on either end face of thestator core 21. By adopting this configuration heat generated in thestator 10 is dissipated via the outer connection coils 41, therebymaking it possible to cool the radially outer coil bar 26 and theradially inner coil bar 27 uniformly. The stator 10 can be cooledfurther efficiently when the cooling plates 60 are disposed so as to bein contact with the outer connection coils 41 which are situated at theaxial outer ends of the stator 10.

Additionally, the outer connection coil 41 connected to the radiallyouter coil bar 26 at the one end thereof extends radially outwards andin one of the clockwise direction and the counterclockwise direction tothereby be connected to the inner connection coil 42 of the same phase,the inner connection coil 42 connected to the radially outer coil bar 26at the other end thereof extends radially outwards and in the other ofthe clockwise direction and the counterclockwise direction to thereby beconnected to the outer connection coil 41 of the same phase, the innerconnection coil 42 connected to the radially inner coil bar 27 at theone end thereof extends radially outwards and in the other of theclockwise direction and the counterclockwise direction to thereby beconnected to the outer connection coil 41 of the same phase, and theouter connection coil 41 connected to the radially inner coil bar 27 atthe other end thereof extends radially outwards and in the one of theclockwise direction and the counterclockwise direction to thereby beconnected to the inner connection coil 42 of the same phase. By adoptingthis configuration, the outer and inner connection coils 41, 42 can beconnected to the coil bars 26, 27 which extend from the slot 23 radiallyoutwards of the outer and inner coil bars 26, 27, and the rotor caneasily be disposed inside the stator 10, thereby making it possible toconnect the connection coils 40 with the coil bars 25 in the form of awave winding.

Additionally, in each of the base plates 31L, 31R, the radially innerthrough hole 33 and the radially outer through hole 32 in which theradially inner coil bar 27 and the radially outer coil bar 26 which aredisposed in the same slot 23 in the stator core 21 are inserted,respectively, are formed so as to be aligned in the radial direction,and the inner connection coil 42 and the outer connection coil 41 whichare connected to the radially outer coil bar 26 are formed so as toextend along the involute curve. Further, the inner connection coil 42and the outer connection coil 41 which are connected to the radiallyinner coil bar 27 are formed so as to extend along the involute curvewhile being bent on the radially inner side of the involute curve so asto extend radially outwards from the radially inner through hole 33while extending around the radially outer through hole 32. Therefore,the inner connection coil 42 and the outer connection coil 41 do notinterfere with each other within each of the base plates 31L, 31R,thereby making it possible to reduce the area occupied by them.

In addition, the radially outer coil bar 26 and the radially inner coilbar 27 are made to have the same length, whereby parts for coil bars 25can be commonized.

Additionally, the plural connection coils 40 are disposed within theregion where the stator core 21 is projected in the axial direction, andtherefore, the size of the stator 10 in the radial direction can bereduced. Additionally, the rotor can easily be disposed inside thestator 10.

It should be noted that the invention is not limited to the embodimentthat has been described heretofore and hence can be modified or improvedas required.

For example, in the embodiment, 12 connecting terminal joining holes 39are formed. However, the invention is not limited thereto, and hence, aconfiguration may be adopted in which six connecting terminal joiningholes 39 are formed, and adjacent connection coils of the same phase areconnected together.

Additionally, an insulation cover may be disposed at the axially outerends of the pair of base plate assemblies 30L, 30R. Alternatively, theaxially outer ends may be covered with a resin or the like.

The stator 10 of the invention is not limited to the double-slot typestator that has been described above. For example, the stator 10 can beconfigured as a single-slot type stator of which the shape of coils ofone phase is shown in FIG. 15 or can be configured as a triple-slot typestator of which the shape of coils of one phase is shown in FIG. 16. Ina three-phase, eight-pole, wave wound stator, in the case of thesingle-slot type stator, the number of slots in the stator core 21 is24, and in the case of the triple-slot type stator, the number of slotsin the stator core 21 is 72.

1. A stator for an electric rotary machine comprising: a stator corehaving a plurality of slots; and segmented coils of a plurality ofphases, wherein: the segmented coils of a plurality of phases havepluralities of coil bars which are inserted individually in theplurality of slots in the stator core and which extend substantially ina straight line and pluralities of connection coils which connecttogether the coil bars of the same phase to thereby make up extendingportions; the connection coils each comprise an inner connection coiland an outer connection coil which are disposed in different axialpositions; and the inner connection coil faces an outer connection coilof a different phase in an axial direction and the outer connection coilfaces the inner connection coil of a different phase in the axialdirection.
 2. The stator core for an electric rotary machine accordingto claim 1, wherein: a pair of base plates are provided at both ends ofthe stator core; in each of the pair of base plates, a plurality ofgrooves are formed on each of an outer surface and an inner surfacethereof which face each other; the outer connection coils are disposedin the grooves which are formed on the outer surface; and the innerconnection coils are disposed in the grooves which are formed on theinner surface.
 3. The stator for an electric rotary machine according toclaim 1, wherein: the coil bars which are inserted individually in theslots each comprise a radially outer coil bar and a radially inner coilbar which are aligned in a radial direction; one of the radially outercoil bar and the radially inner coil bar is connected to the outerconnection coil at one end and is connected to the inner connection coilat the other end thereof; and the other of the radially outer coil barand the radially inner coil bar is connected to the inner connectioncoil at one end and is connected to the outer connection coil at theother end thereof.
 4. The stator for an electric rotary machineaccording to claim 3, wherein: the outer connection coil connected tothe radially outer coil bar at the one end thereof extends radiallyoutwards and in one of a clockwise direction and a counterclockwisedirection to thereby be connected to an inner connection coil of thesame phase; the inner connection coil connected to the radially outercoil bar at the other end thereof extends radially outwards and in theother of the clockwise direction and the counterclockwise direction tothereby be connected to an outer connection coil of the same phase; theinner connection coil connected to the radially inner coil bar at theone end thereof extends radially outwards and in the other of theclockwise direction and the counterclockwise direction to thereby beconnected to an outer connection coil of the same phase; and the outerconnection coil connected to the radially inner coil bar at the otherend thereof extends radially outwards and in the one of the clockwisedirection and the counterclockwise direction to thereby be connected toan inner connection coil of the same phase.
 5. The stator for anelectric rotary machine according to claim 4, wherein: in each of thebase plates, a radially inner through hole and a radially outer throughhole in which the radially inner coil bar and the radially outer coilbar which are disposed in the same slot in the stator core are inserted,respectively, are formed so as to be aligned in the radial direction;the inner connection coil and the outer connection coil which areconnected to the radially outer coil bar are formed so as to extendalong an involute curve; and the inner connection coil and the outerconnection coil which are connected to the radially inner coil bar areformed so as to extend along an involute curve while being bent at aradially inner end of the involute curve so as to extend radiallyoutwards from the radially inner through hole while extending around theradially outer through hole.
 6. The stator for an electric rotarymachine according to claim 3, wherein the radially outer coil bar andthe radially inner coil bar have the same length.
 7. The stator for anelectric rotary machine according to claim 1, wherein the pluralities ofconnection coils are disposed within a region where the stator core isprojected in the axial direction.